How can I use a green screen to add a video onto a moving plane?
No need to use afterFX for this.
The idea is quite simple.
You use green, or some color that is not present in the scene, to create a matte (or mask) that can be used to combine other elements in the scene.
In the compositor connect the image that has the green element add a keying node, select the key color and the node will output Image and Matte separately.
Use the Matte to control the mix between the tracked plane and the image.

Or use just use the mask and feed the original image. This setup will avoid correlated alpha issues.